Refrigerator and control method thereof

A refrigerator comprising:

• a main body;
• a door rotatably coupled to the main body with respect to a hinge shaft;
• a door operation device configured to open the door;
• a door sensor configured to detect whether the door is opened or closed;
• and
• a controller configured to control the door operation device,
• wherein the door operation device includes:
• a pressure device configured to press the main body so as to open the door;
• and
• a drive device including a power generation device configured to generate power, and a power transmission device configured to transmit the power to the pressure device and the hinge shaft,
• wherein the controller is configured to:
• operate the power generation device with a first output value to open the door based on a door opening signal transmitted from the door sensor, and
• operate the power generation device with a second output value smaller than the first output value, when a first time elapses after the door is closed.